A Rigorous Thermodynamic Property Model for Fluid-Phase 1,1-Difluoroethane (R-152a)

Abstract

A new thermodynamic property model for the Helmholtz free energy with rational third virial coefficients for fluid-phase 1,1-difluoroethane (R-152a) was developed. The model was validated by existing experimental data for temperatures from the triple point to 450 K and pressures up to 60 MPa. Reasonable behavior of the second and third virial coefficients was confirmed from intermolecular potential models. The estimated uncertainties are 0.1% in density for the gaseous and liquid phases, 0.4% in density for the supercritical region, 0.05% in speed of sound for the gaseous phase, 2% in speed of sound for the liquid phase, and 1% in specific heat capacities for the liquid phase. From the reasonable behavior of the ideal curves and the third virial coefficients, the model can be assumed reliable in representing the thermodynamic properties not only at states with available experimental data but also at states for which no experimental data are available.

Theoretical estimation of the isobaric heat capacity cp of refrigerant

“…It's worthwhile to mention that several existing equations of state are available for calculating thermodynamic properties including c p , which could be distributed MBWR-type EoS [1][2][3][4][5], Helmholtz-type EoS [6][7][8][9][10][11][12] and the virial equation of state [13]. Additional in recent years, aiming at candidate refrigerants, some new equation models were established on the basis of not only assessment of the experimental data but also by introducing parameters for virial coefficients having a theoretical background in statistical thermodynamics [14][15][16]. Then especially for mixing refrigerants R407C and R410A, a theoretical development of the thermodynamic properties was introduced in the literature [17,18].…”